Tomato Early Blight

Early blight is very common in the Northeast and occurs there to some extent wherever tomatoes are grown. Although it’s called “early blight,” it can actually occur any time during the growing season attacking the leaves, stems and fruit. It can also cause disease on its nightshade cousins; potatoes, peppers and eggplants.

Causes and symptoms

Tomatoes with early blight will have irregular circular black or brown spots on the older leaves. Symptoms are usually visible 10 days after infection. As the disease progresses the spots will begin to develop rings creating a target pattern. Over time, the blight turns yellow and the leaves drop off leaving the fruit to scald in the sun.

Early blight also affects the fruit of the tomato plant. Sunken dark leathery spots appear first on the stem end. The rot goes deep into the flesh of the tomato and eventually the fruit will drop. The disease will overwinter on plant debris and warm moist weather conditions will cause it to thrive. It often enters the plant through a cut bruise of wounded area so pest control is very important.

Treatment and Control

Plant only disease free seed and follow a good fungicide regimen. Use only fungicide recommended for early blight and follow the instructions carefully.

The best control is good cultural practice. Always remove old plant debris and do not compost. Keep leaves of tomato plants from touching the ground, rotate crops, cover with at least 6 inches of mulch during the growing season to keep plants from touching the soil. Always space plants to allow good air circulation so the plants will dry quickly after rainfall or irrigation.

If early blight is a problem in your area, look for cultivars that are resistant to this disease like Mountain Fresh, Mountain Supreme and Plum Dandy.